In general, in a hybrid electric vehicle (HEV) adopting a cell in an internal combustion engine as a partial driving source or an electric vehicle (EV) using a cell as a main driving source, performance of the vehicles depends on how the cell is maintained under optimal conditions to produce a maximum output.
For example, as shown in FIG. 1, a conventional air conditioning device 1 for a battery pack comprises: a battery pack 5 consisting of a plurality of cells (not shown) and a case 4 accommodating each of the cells so that there is secured an air flow passage between the neighboring cells and having an air inlet 2 at one side thereof and an air outlet 3 at the other side thereof; an air filter 6 detachably mounted around the air inlet 2; a blowing fan 7 provided to the air outlet 3; a temperature sensor 8 arranged around the air inlet 2 and detecting heat generated from the battery pack 5; and a control unit (such as BMS) 9 connected to the cells of the battery pack 5, the blowing fan 7 and the temperature sensor 8, respectively, measuring currents, voltages and temperatures of the respective cells and electrically controlling the blowing fan 7 and the temperature sensor 8.
The control unit 9 detects the heat generated from the battery pack 5 through the temperature sensor 8 when the battery pack 5 is discharged or charged. At this time, when the heat generated from the battery pack is within a normal temperature range, the control unit continues to control the blowing fan 7 under corresponding operating mode as it is, and when the heat is out of the normal temperature range, it increases/decreases the output of the blowing fan 7 so that the temperature of the battery pack 5 reaches the normal range.
However, according to the prior art, since there is provided only the temperature sensor connected to the control unit in the air inlet, it is impossible to precisely detect the non-mounted state or replacement time of the air filter. Accordingly, even though a lot of dusts are adhered to the air filter, an operator or user cannot perceive such situations in advance, so that there occurs degradation or reduction in lifetime of the battery pack.